Project Summary In spite of the prevalence and severity of many neurological disorders, the development of new classes of drugs has been sluggish for decades. The lack of new therapeutics is due, in part, to challenges in replicating the relevant biology in robust, scalable in vitro assays. Synaptic dysfunction, in particular, has been implicated in a number of devastating neurological disorders including epilepsy, Alzheimer?s disease, Parkinson?s disease, Autism Spectrum Disorder (ASD), schizophrenia, depression, ADHD and Huntington?s disease. Current approaches to measuring synaptic function suffer from the difficulty of stimulating the pre-synaptic cell and recording from the post-synaptic cell at a sufficient throughput for drug screening. The Optopatch platform recently developed at Q-State Biosciences, comprised of both engineered optogenetic proteins, custom microscopes, and software, makes it possible to simultaneously stimulate (blue light) and record (red light) electrical activity from around one hundred neurons with one millisecond temporal resolution, single cell spatial resolution and high signal-to-noise. Patterned blue light can be used to stimulate one or a larger subset of neurons while recording from all of the synaptic partners. Using a custom engineered channelrhodopsin for stimulation in combination with red fluorescent sensors of voltage, calcium and pH targeted to pre- and post-synaptic locations, we will develop a set of assays that span synaptic function. Furthermore, we will probe short- and long-term synaptic plasticity using different stimulus regimes. To validate the assays, we will test know pharmacological modulators of synaptic machinery. We will also test for an in vitro phenotype for knockout of a post-synaptic scaffolding protein, SHANK3, whose loss of function has been implicated in ASD and schizophrenia. We will use both mouse and human iPSC-based models of diseased neurons. These optical tools, which can scale to high throughput, have the potential to change the drug screening landscape for neurological disorders. We hope to open a new path to finding treatments for these devastating diseases.